ORAU TEAM

Dose Reconstruction

Project for NIOSH

Oak Ridge Associated Universities I Dade Moeller I MJW Technical Services

Page 1 of 21

DOE Review Release 08/26/2009

Document Title:

Coworker External Dosimetry Data for 

the Y-12 National Security Complex

Document Number: ORAUT-OTIB-0064

Revision: 00 

Effective Date: 08/03/2009

Type of Document OTIB

Supersedes: None

Subject Expert(s): Janice P. Watkins, Edward L. Frome, George D. Kerr, William G. Tankersley

Site Expert(s): N/A

Approval: Signature on File Approval Date: 06/22/2009

Janice P. Watkins, Document Owner

Concurrence: Signature on File Concurrence Date: 06/22/2009

John M. Byrne, Objective 1 Manager

Concurrence: Signature on File Concurrence Date: 06/24/2009

Edward F. Maher, Objective 3 Manager

Concurrence: Signature on File Concurrence Date: 06/23/2009

Kate Kimpan, Project Director

Approval: Signature on File Approval Date: 08/03/2009

James W. Neton, Associate Director for Science

 New Total Rewrite Revision Page Change

FOR DOCUMENTS MARKED AS A TOTAL REWRITE, REVISION, OR PAGE CHANGE, REPLACE THE PRIOR 

REVISION AND DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 2 of 21

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

08/03/2009 00 Approved new technical information bulletin that provides 

background information on the Y-12 coworker external dosimetry 

data and includes tables with annual values that may be used in the 

process of assigning doses for unmonitored years of employment. 

Incorporates formal internal and NIOSH review comments. Training 

required: As determined by the Objective Manager. Initiated by 

Janice P. Watkins.
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 3 of 21

TABLE OF CONTENTS

SECTION TITLE

Acronyms and Abbreviations ...............................................................................................................

PAGE

5

1.0 Introduction ..............................................................................................................................6

2.0 Purpose and Scope..................................................................................................................6

3.0 Background..............................................................................................................................6

4.0 General Approach....................................................................................................................7

5.0 Applications and Limitations.....................................................................................................7

6.0 Coworker Data Development ...................................................................................................8

6.1 Adjustment for Missed Dose.......................................................................................10

6.2 Other Considerations..................................................................................................13

7.0 Coworker Annual Dose Summaries ....................................................................................... 13

8.0 Attributions and Annotations .................................................................................................. 17

References ........................................................................................................................................19
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 4 of 21

LIST OF TABLES

TABLE TITLE

6-1 Comparisons of distributions of annual gamma doses and annual skin doses in 1962.............

PAGE

9

6-2 Exchange frequencies for film badge dosimeters as a function of time................................... 12

6-3 MDLs and assigned MDL doses for film used to measure gamma and beta doses................ 12

6-4 Potential missed dose from external radiation exposure during the film badge dosimetry 

program ................................................................................................................................. 13

7-1a Parameters for lognormal prediction density, 1947 to 1949.................................................... 15

7-1b Annual coworker external doses with gamma and beta doses adjusted for missed dose 

by the method in ORAUT-OTIB-0020..................................................................................... 15

7-2 Annual coworker external doses with gamma and beta doses modified for construction 

trade workers in accordance with ORAUT-OTIB-0052 ........................................................... 16

LIST OF FIGURES

FIGURE TITLE

6-1 Comparison of cumulative skin doses in rem from UCNC (1957) and the CER database 

for 65 foundry workers, 1952 to 1956.......................................................................................

PAGE

9

6-2 Percentage of null penetrating and nonpenetrating doses among the recorded quarterly 

doses, 1950 to 1964...............................................................................................................11

6-3 Percentage of null penetrating and nonpenetrating doses among the recorded quarterly 

doses, 1965 to 1979...............................................................................................................11
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 5 of 21

ACRONYMS AND ABBREVIATIONS

CER Center for Epidemiologic Research

DOE U.S. Department of Energy

E (dose) the expected value of dose in the statistical sense, i.e., the mean dose on the original 

scale 

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000

GM geometric mean

GSD geometric standard deviation

HP health physics

IREP Interactive RadioEpidemiological Program

keV kiloelectron-volt (1,000 electron-volts)

K-25 Oak Ridge Gaseous Diffusion Plant

MDL minimum detectable level

mrem millirem

NIOSH National Institute for Occupational Safety and Health

ORAU Oak Ridge Associated Universities

SRDB Ref ID Site Research Database Reference Identification (number)

SSN Social Security Number

TBD technical basis document

TIB technical information bulletin

TLD thermoluminescent dosimeter 

U.S.C. United States Code

wk week

X-10 Oak Ridge National Laboratory

Y-12 Y-12 Plant, now the Y-12 National Security Complex

yr year

§ section or sections
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 6 of 21

1.0

Technical information bulletins (TIBs) are not official determinations made by the National Institute for 

Occupational Safety and Health (NIOSH) but are rather general working documents that provide 

historic background information and guidance to assist in the preparation of dose reconstructions at 

particular sites or categories of sites. They will be revised in the event additional relevant information 

is obtained about the affected site(s). TIBs may be used to assist NIOSH staff in the completion of 

individual dose reconstructions.

INTRODUCTION

In this document, the word “facility” is used as a general term for an area, building, or group of 

buildings that served a specific purpose at a site. It does not necessarily connote an “atomic weapons 

employer facility” or a “Department of Energy (DOE) facility” as defined in the Energy Employees 

Occupational Illness Compensation Program Act of 2000 [42 U.S.C. § 7384l(5) and (12)].

2.0

The purpose of this TIB is to provide information that will enable Oak Ridge Associated Universities 

(ORAU) Team dose reconstructors to assign doses based on site coworker data to workers at the 

Y-12 Plant who have limited or no monitoring data. The data in this TIB are to be used in conjunction 

with ORAUT-OTIB-0020, Use of Coworker Dosimetry Data for External Dose Assignment (ORAUT 

2008). This TIB is for use in reconstructions for the period from January 1950 to December 1979.

PURPOSE AND SCOPE

Attributions and annotations, indicated by bracketed callouts and used to identify the source, 

justification, or clarification of the associated information, are presented in Section 8.0. 

3.0

The ORAU Team is conducting a series of coworker data studies to permit dose reconstructors to 

complete cases for which external and/or internal monitoring data are unavailable or incomplete. 

Such cases can fall into one of several categories, as follows: 

BACKGROUND

• The worker was unmonitored and, even by today’s standards, did not need to be monitored 

(e.g., a nonradiological worker). 

• The worker was unmonitored but by today’s standards would have been monitored. 

• It is possible that the worker was monitored, but if so the data are not available. 

• There is some information available for the worker, but it is insufficient to permit a dose 

reconstruction.

The Union Carbide Corporation Nuclear Division assumed the management of the Y-12 Plant in May 

1947, and the Plant mission changed from the electromagnetic enrichment of uranium using calutrons 

to the processing and fabrication of uranium and other nuclear materials (ORAUT 2007a). The first 

experience with the machining of uranium metal at the Y-12 Plant was in December 1947 in a shop in 

Building 9766 (Emlet 1952). In the spring of 1948, steps were taken for the transfer of certain weapon 

fabrication functions from Los Alamos to Y-12 Plant facilities, which were established in Building 9212 

where chemical processing of uranium had long occurred. At that time, the responsibility for the study 

and monitoring of the uranium machining operations was transferred from a Special Hazards Group to 

a Health Physics (HP) Department in the Medical Division (Emlet 1952).
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 7 of 21

The HP Department started a film badge dosimetry program in 1948 to monitor external radiation 

exposures to Y-12 workers in the Assay Laboratories, Radiographic Shop, Spectrographic Shop, and 

Machine Shops, which handled uranium metals (Struxness 1948). The external monitoring data for 

1948 and 1949 are not readily available by Social Security Number (SSN), and have not been

supplied by Y-12 in response to requests under the Energy Employees Occupational Illness 

Compensation Program Act of 2000 (EEOICPA) (Souleyrette 2003). A report of the external 

monitoring data for 1948 and 1949 that are available from previous epidemiological studies by the 

ORAU Center for Epidemiologic Research (CER) has been published (ORAUT 2005a). The CER 

data have been placed on the secure data server at the ORAU Cincinnati Operations Office for use in 

dose reconstructions for workers at the Y-12 facility. In addition, the data on the server have been 

linked to each worker’s badge identification number and SSN (ORAUT 2005a).

An extensive documentation of the worker radiological programs beginning in the 1950s is provided in 

the Recycled Uranium Mass Balance Project for the Y-12 National Security Complex Site Report

(BWXT Y-12 2000). The film badge dosimetry program was expanded in 1950 to include all Y-12 

personnel who worked with (1) depleted uranium metal, (2) discrete sources of gamma rays or beta 

particles, (3) X-rays, and (4) materials that were contaminated with fission products (McLendon 1960). 

The external radiation dosimetry policy of monitoring only the Y-12 workers involved the four types of 

radioactive materials listed above (about 10% to 20%) was continued until 1961 (ORAUT 2005b). In 

1961, a new policy was instituted that required all Y-12 workers to be monitored for external radiation 

exposure with film dosimeters, which were integrated into the worker’s identification badges and 

contained components for both routine and accident-related dosimetry. The use of film dosimeters 

ended in 1979 when they were largely replaced by thermoluminescent dosimeters (TLDs) (McLendon 

et al. 1980; West 1993).

4.0

As described in ORAUT (2008), the general approach to the application of coworker data to cases 

without external monitoring data involves two phases. Phase I permits the processing of cases when 

a “best-and-final” estimate of dose is not required for claim determination. Phase II facilitates the 

assignment of best-and-final estimates of dose, when necessary. This TIB provides coworker 

external dosimetry summary statistics applicable to Phase I dose reconstructions. Dose distributions 

applicable to Phase II dose reconstructions can be obtained from tables available in ORAUT-RPRT0032, Historical Evaluation of the Film Badge Dosimetry Program at the Y-12 Facility in Oak Ridge: 

Part 1 – Gamma Radiation (ORAUT 2005b), for gamma doses and ORAUT-OTIB-0046, Historical 

Evaluation of the Film Badge Dosimetry Program at the Y-12 Plant in Oak Ridge, Tennessee: Part 3 

– Beta Radiation (ORAUT 2007a), for beta doses.

GENERAL APPROACH

5.0

1. The coworker data and information in this report can be used only for dose reconstruction 

cases that do not require best-estimate calculations [1]. Such cases include evidently 

noncompensable cases for which a higher external dose can be assigned than that likely to 

have been actually received, or evidently compensable cases for which a lower external dose 

can be assigned than that likely to have been actually received. For cases that require a bestestimate analysis, recommended methods based on subgroup regression analyses are 

detailed in ORAUT (2005b) and ORAUT (2007a). These documents provide tables of 

geometric means (GMs) and geometric standard deviations (GSDs) that begin with the third 

quarter of 1947. 

APPLICATIONS AND LIMITATIONS
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 8 of 21

2. Some workers might have been employed at more than one of the major DOE sites in the Oak 

Ridge area (K-25, X-10, and Y-12). For some cases, employment information is provided in 

the NIOSH Office of Compensation Analysis and Support Claims Tracking System as a 

multiple site listing such as “K-25/Y-12/X-10,” and the available information such as the DOE 

dosimetry records and claimant interview are insufficient to determine the actual work 

location(s), especially on an annual basis. Similarly, workers might have worked at more than 

one major site across the DOE complex during their employment history. Therefore, the data 

in this document must be used with caution to ensure, for evidently noncompensable and 

evidently compensable cases, that unmonitored external radiation exposures from multiple site 

employment have been overestimated and underestimated, respectively.

3. The summary statistics in this TIB extend from 1950 through 1979, the end of the film badge 

dosimetry program at the Y-12 Plant. The absence of data for 1980 and later (and subsequent 

development of other dose distributions) should not interfere with the processing of most Y-12 

cases that have a lack of external dosimetry data because in recent years the TLD monitoring 

programs at Y-12 and the other Oak Ridge sites were sufficiently comprehensive to ensure 

that a dose reconstruction can be carried out for all workers with a potential for external 

exposure during the TLD dosimetry period [2]. 

4. The data in this TIB address gamma doses (i.e., the radiation doses from gamma rays and 

hard X-rays) and beta doses (i.e., the radiation from beta particles and soft X-rays). Neutron

dose data are not presented. However, the locations at the Y-12 site at which neutron 

exposures were possible are limited (ORAUT 2005c), and neutron doses were monitored 

separately for Y-12 workers who had a potential for neutron exposure (Emlet 1956). 

Therefore, it is not likely that the lack of coworker data for external radiation exposure to 

neutrons in this TIB would negatively affect Y-12 dose reconstructions [3]. 

6.0

From 1978 through the early 1990s, the Y-12 site delivered electronic files of worker data to the 

ORAU CER as a resource for the Health and Mortality Studies for DOE and its predecessor agencies 

(Watkins et al. 1993). Files that were received on magnetic tapes contained records for more than 

17,000 Y-12 workers. The records included doses from gamma, beta, and neutron exposures as well 

as other relevant information. Due to changes over time in recordkeeping practices and procedures 

at Y-12, the files were in several similar but not identical formats. CER transferred all the data from 

tape to disk and later constructed a carefully linked relational database with a standardized file format. 

Since 2002, the data have resided in a Structured Query Language database. The data that were 

used in this work consist of more than 425,000 records for 1950 through 1979. All records contain the 

data elements from original Y-12 files, which included first, middle, and last name; plant badge 

number; SSN; year; quarter; quarterly summations of dose readings for different monitoring periods 

(i.e., weekly, monthly, or quarterly); and other work history and demographic data. The quarterly 

summations give results in millirem for all beta, gamma, and neutron doses. Although each record 

has a flag to note an error condition, this flag is null for years before 1980 and so is not relevant for 

the film badge period. The external radiation doses that are being provided to NIOSH are effectively 

the same as those in the CER database.

COWORKER DATA DEVELOPMENT

The validity of the CER database was confirmed by a number of comparisons with summaries of film 

badge dose data in Y-12 internal correspondence and Y-12 HP progress reports [4]. The progress 

reports were produced with varying frequency (monthly, quarterly, and semiannually) and have been 

retrieved from as early as September 1947 (Murray 1947). Examples of such comparisons are 

provided in Table 6-1 and Figure 6-1. The left-hand portion of Table 6-1 lists the distribution of annual 
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 9 of 21

gamma doses and annual skin doses (i.e., annual gamma dose plus annual beta dose) to Y-12 

workers during 1962 from a progress report for the fourth quarter of 1962 (UCNC 1963a). The rightTable 6-1. Comparisons of distributions of annual gamma doses and annual skin 

doses (gamma plus beta radiation) in 1962. 

HP progress report (UCNC 1963a) CER database

Dose range 

(mrem)

Number of workers Dose range 

(mrem)

Number of workers

Gamma Skin dose Gamma Skin dose

<1,000 5,787 5,108 0–1,000 5,771 4,990

2,000 6 324 1,001–2,000 20 403

3,000 1 173 2,001–3,000 2 197

4,000 0 91 3,001–4,000 1 98

5,000 0 40 4,001–5,000 0 43

6,000 0 25 5,001–6,000 0 28

7,000 0 15 6,001–7,000 0 16

8,000 0 9 7,001–8,000 0 10

9,000 0 6 8,001–9,000 0 6

10,000 0 2 9,001–10,000 0 2

11,000 0 0 10,001–11,000 0 1

12,000 0 1 11,001–12,000 0 0

>12,000 0 0 >12,000 0 0

Total 5,794 5,794 Total 5,794 5,794

Figure 6-1. Comparison of cumulative skin doses in 

rem (Srem) from UCNC (1957) and the CER 

database for 65 foundry workers, 1952 to 1956. 

hand portion of Table 6-1 lists the same annual dose distributions from the CER database. The two 

sets of annual dose distributions in Table 6-1 are in excellent agreement. The second example, 

shown in Figure 6-1, is from internal correspondence on the radiation doses to Y-12 foundry workers 
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 10 of 21

(UCNC 1957). The open circles in Figure 6-1 represent a comparison of cumulative skin doses to 65 

Y-12 foundry workers over the 5-year period from 1952 to 1956 from UCNC (1957) and those derived 

from sums of 194 person-years of recorded skin dose data over the same period and for the same 65 

Y-12 foundry workers. The two sets of cumulative skin doses have high correlation as Figure 6-1 

shows. The Pearson correlation coefficient, which assumes a bivariate normal distribution, is 0.841 

(Pearson 1896), and the nonparametric Spearman (rank) correlation coefficient is 0.975 (Spearman 

1904). Overall, the CER database was found to be acceptable for dose reconstruction purposes and 

for the development of coworker doses at the Y-12 Plant for 1950 to 1979. 

6.1 ADJUSTMENT FOR MISSED DOSE

The External Dose Reconstruction Implementation Guideline (NIOSH 2007) states that missed doses 

are to be assigned for null dosimeter readings to account for the possibility that doses were received 

but either not recorded by the film badge dosimeter or not reported by the site. These missed doses 

are calculated by multiplying the minimum detectable level (MDL) of the dosimeters by the number of 

null badge readings and summing the results; these values are used as the 95th-percentile values of 

a lognormal distribution for calculating probability of causation for a specific cancer. Therefore, in the 

Interactive RadioEpidemiological Program (IREP), the calculated missed doses should be multiplied 

by 0.5 and entered in Parameter 1 (the GM), and 1.52 should be entered in Parameter 2 (the GSD). 

The assignment of missed doses for monitored workers is particularly significant for Y-12 workers, as 

shown in Figures 6-2 and 6-3, because historically there was a high percentage of null dosimeter 

results for this site. The large number of null results in the monitoring data is largely due to the weekly 

exchange of film badge dosimeters for monitored workers in the early 1950s and to the monitoring of 

the entire Y-12 workforce with film badge dosimeters staring in 1961. Because Y-12 workers with null 

monitoring data should be assigned missed dose, including those workers who probably had no 

potential for exposure to external radiation during their employment, the assignment of doses to Y-12 

workers with no monitoring data based on coworker data must also account for the assignment of 

missed dose [5]. 
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 11 of 21

Figure 6-2. Percentage of null penetrating (gamma) and nonpenetrating

(beta) doses among the recorded quarterly doses, 1950 to 1964. 

Figure 6-3. Percentage of null penetrating (gamma) and nonpenetrating 

(beta) doses among the recorded quarterly doses, 1965 to 1979. 
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 12 of 21

The development of coworker data for the Y-12 Plant invoked a need to revise the MDLs and the 

exchange frequencies of the film badge dosimeters at the plant [6]. These revised dates for changes 

in the film badge exchange frequencies are provided in Table 6-2. 

Table 6-2. Exchange frequencies for film badge dosimeters

as a function of time.

a

Periodb Exchange frequency

May 1948–September 1958 Weekly

October 1958–December 1960 Monthly

January 1961–December 1979 Quarterly

a. ORAUT (2005a), West (1993), McLendon (1958), and Reavis (1958).

b. Dates are approximate because changes did not occur for all employees 

at the same time.

The revised dates for changes in the estimated MDL of the film badge dosimeters are listed in 

Table 6-3. It is important to note that the MDL and the assigned MDL dose to workers changed 

significantly with time. As noted, the dates are approximate because the changes did not occur for all 

employees at the same time. In 1950 and 1951, doses were recorded as zero if they were less than 

the MDL of 30 mrem (see Table 6-3). As a result, there was only one positive gamma dose of 

65 mrem among the 268 recorded quarterly doses for the 148 monitored workers in 1950, and no 

positive gamma doses were recorded for the 184 monitored workers in 1951. There were also no 

beta doses recorded for these monitored workers in either 1950 or 1951 (see Figure 6-2). 

Table 6-3. MDLs and assigned MDL doses (mrem) for film

used to measure gamma and beta doses.

a

Periodb MDL Assigned dose

May 1948–December 1949 30 30c

January 1950–December 1951 30 0

January 1952–September 1952 50 50c

October 1952–December 1952 43 43c

January 1953–June 1954 50 50c

July 1954–December 1954 30 30c

January 1955–December 1957 30 15d

January 1958–October 1979 30 Not applicablee

a. ORAUT (2005a); West (1993).

b. Dates are approximate because the changes did not occur for all 

employees at the same time.

c. Assigned to gamma dose for those workers with a high potential for 

exposure to gamma rays or to beta dose for those workers with a 

high potential for exposure to beta particles (or soft X-rays) if 

shielded and open-window film readings were less than the MDL.

d. Assigned to beta dose if shielded and open-window film readings 

were less than the MDL.

e. The actual shielded and open-window film readings were used to 

calculate the gamma and beta doses even when the film readings 

were less than the MDL.

The data in Tables 6-2 and 6-3 were used in the development of the data in Table 6-4, which lists the 

maximum annual missed gamma and beta doses by period. Although some workers might have been 

on a film dosimeter exchange cycle that was less or more frequent than the typical cycle (ORAUT 

2006), the great majority of Y-12 workers were on the schedule listed in Table 6-2. Therefore, the 

values in Table 6-4 are appropriate for the adjustment of reported coworker doses to account for 

missed dose. 
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 13 of 21

Table 6-4. Potential missed dose (mrem) from external radiation exposure during the film 

badge dosimetry program. 

Period

Gamma 

MDL

Beta 

MDL

Exchange 

frequency

Maximum annual missed dose 

Gamma (mrem) Beta (mrem)

May 1948–Dec 1949 30 30 Weekly 1560 1560

Jan 1950–Dec 1951 30 30 Weekly 1560 1560

Jan 1952–Sep 1952 50 50 Weekly 2600 2600

Oct 1952–Dec 1952 43 43 Weekly 2236 2236

Jan 1953–Jun 1954 50 50 Weekly 2600 2600

Jul 1954–Sep 1958 30 30 Weekly 1560 1560

Oct 1958–Dec 1960 30 30 Monthly 360 360

Jan 1961–Dec 1979 30 30 Quarterly 120 120

6.2 OTHER CONSIDERATIONS

Certain aspects of the external dosimetry practices at the Y-12 Plant that are documented in the 

external radiation TBD for the Y-12 site (ORAUT 2006) were considered in the analysis of the site 

data. These include:

• In some cases, values less than the dosimeter MDL were reported by the site. A lower 

detection limit of approximately 10 mrem was possible if an experienced technician evaluated 

the exposed film with special care (Morgan 1961). Therefore, values as low as 10 to 20 mrem 

were reported even though the MDL was considered to be 30 mrem or more.

• Before 1961, dosimeter use was not expressly required for all workers. Badges were typically 

provided only to people who entered a radiation area, and the badges were worn based on an 

honor system rather than on a strict requirement. A review of worker data indicates that most 

workers did wear the badges when they were provided.

As described in Section 7.0, the approach for the development of coworker dose summaries was 

favorable to claimants, and this approach should account for any underestimates of doses to radiation 

workers at the Y-12 site based on these considerations.

7.0

Based on the information and approaches described above, Y-12 coworker annual external dosimetry 

summaries were developed for use in the evaluation of external dose for workers who were potentially 

exposed to workplace radiation but for whom DOE could not provide monitoring data. These 

summaries were developed as follows:

COWORKER ANNUAL DOSE SUMMARIES 

1. The gamma and beta doses available from CER (see Section 6.0) were converted to annual 

data by summing the reported quarterly data for 1950 to 1979. Consistent with the guidelines 

in ORAUT-OTIB-0020 (ORAUT 2008), gamma and beta doses for individuals with fewer than 

4 quarters of data for a particular year were converted to annual doses by extrapolation: One 

quarterly result was multiplied by 4; the sum of two quarterly results was multiplied by 2; and 

the sum of three quarterly results was multiplied by 1.333. 

2. For the gamma doses, one-half of the year’s maximum possible annual missed dose was 

added to each annual dose from Step 1 using the MDLs and badge exchange frequencies in 

Tables 6-2 and 6-3. The added amount for a quarter was the MDL/2 multiplied by the badge 

exchange frequency. If a reported quarterly dose was positive, the badge exchange frequency 
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 14 of 21

was reduced by 1 because it is not possible that all individual badge results were zero if a 

positive annual dose was reported. Note that this is not the procedure described in OCAS-IG001 (NIOSH 2007, Section 2.1.2.3), which applies to situations in which the number of zero 

measurements cannot be determined, as occurs for Y-12 doses before 1961.

3. The 50th- and 95th-percentile annual gamma and beta dose values were derived from the 

gamma and beta doses in Step 2 by ranking the data and extracting percentiles for each year. 

4. The results are presented in Table 7-1a and 7-1b for both gamma and beta doses. The 

gamma dose percentiles should be used for selected Y-12 workers with limited or no 

monitoring data using the methods in Section 7.0 of ORAUT-OTIB-0020 (ORAUT 2008). The 

percentiles for beta doses should be applied only to Y-12 workers who were employed in 

areas with beta dose potential.
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 15 of 21

Table 7-1a. Parameters for lognormal prediction density, 1947 to 1949. 

Gamma dosea

Yr Qtr μ σ GM(reg) GSD(reg)

E(dose)

(mrem)

1947 3 5.2684 1.1710 194.1093 3.2254 385.3264

4 5.2380 1.1710 188.3017 3.2251 373.7602

1948 1 5.2077 1.1709 182.6679 3.2248 362.5419

2 5.1773 1.1708 177.2026 3.2245 351.6610

3 5.1469 1.1707 171.9009 3.2243 341.1072

4 5.1165 1.1706 166.7578 3.2240 330.8709

1949 1 5.0862 1.1706 161.7685 3.2238 320.9423

2 5.0558 1.1705 156.9285 3.2235 311.3123

3 5.0254 1.1704 152.2334 3.2233 301.9717

4 4.9950 1.1703 147.6787 3.2230 292.9120

Beta doseb

Yr Qtr μ σ GM(reg) GSD(reg)

E(dose)

(mrem)

1947 3 6.8231 1.3687 918.82 3.9304 2,344.4

4 6.8075 1.3687 904.61 3.9304 2,308.2

1948 1 6.7917 1.3687 890.41 3.9304 2,272.0

2 6.7756 1.3687 876.20 3.9304 2,235.7

3 6.7593 1.3687 862.00 3.9304 2,199.5

4 6.7426 1.3687 847.79 3.9304 2,163.2

1949 1 6.7257 1.3687 833.59 3.9304 2,127.0

2 6.7085 1.3687 819.38 3.9304 2,090.7

3 6.6911 1.3687 805.17 3.9304 2,054.5

4 6.6733 1.3687 790.97 3.9304 2,018.2

a. From ORAUT-RPRT-0032, Rev. 00 (ORAUT 2005b).

b. From ORAUT-OTIB-0046 (ORAUT 2007a).

Table 7-1b. Annual coworker external doses (mrem) for 1950 to 1979 with 

gamma and beta doses adjusted for missed dose by the method in 

ORAUT-OTIB-0020. 

Year

Gamma dose (mrem) Beta dose (mrem) Number of 

monitored 

workers

95th 

percentile

50th 

percentile

95th 

percentile

50th 

percentile

1950 780 780 780 780 148

1951 780 780 780 780 184

1952 3,453 2,419 5623 1,300 497

1953 4,216 1,300 7429 2,475 386

1954 3,608 1,300 11,843 3,039 681

1955 2,572 780 11,482 3,241 623

1956 1,810 961 8,404 2,541 729

1957 1,556 934 7,777 2,384 795

1958 1,797 1,065 4,470 1,745 995

1959 1,173 448 3,928 875 1,265

1960 1,124 423 5,093 894 1,335

1961 491 155 2,322 91 5,869

1962 519 171 2,257 101 5,793

1963 360 58 1,464 82 5,789

1964 397 72 1,578 97 5,592

1965 382 110 1,083 70 5,138
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 16 of 21

1966 478 87 1,185 118 4,730

1967 372 71 1,014 81 5,016

1968 271 141 897 48 5,580

1969 364 127 624 52 6,319

1970 366 122 863 53 7,122

1971 325 110 469 47 7,055

1972 208 57 586 48 6,880

1973 198 53 510 60 6,503

1974 366 93 614 60 5,836

1975 171 54 613 60 5,282

1976 179 58 410 89 5,062

1977 158 52 350 57 5,360

1978 219 86 385 57 5,573

1979 156 60 571 71 5,964

Doses to organs that are affected only by gamma radiation (e.g., organs other than the skin, breast, 

and testes) are calculated based only on the gamma dose columns in Table 7-1a and 7-1b in 

combination with the appropriate organ dose conversion factors (NIOSH 2006). Doses to the skin, 

breast, and testes (or any other cancer location potentially affected by beta radiation) are determined 

based on both the gamma and beta columns; gamma doses are assigned as photons with energy 

ranges consistent with information in the external dosimetry TBD for the Y-12 site (ORAUT 2006), and 

beta doses are assigned as electrons with energy greater than 15 keV (or photons with less than 30 

keV if appropriate) with corrections to account for clothing attenuation or other relevant considerations 

(ORAUT 2005d). Work with depleted uranium has been responsible for the majority of the beta (or 

non-penetrating) doses at the Y-12 facility (UCNC 1963a,b; Henderson 1991; Ashley et al. 1995; 

ORAUT 2007a). 

As footnoted in Table 6-3 and demonstrated in the example in Section 6.2, significant amounts of 

missed dose were already added to the recorded dose of Y-12 workers in the late 1940s and early 

1950s. With the addition of more missed dose to these workers’ recorded doses as outlined above, 

the amount of missed dose that was added to some of these workers’ recorded doses from January 

1952 to September 1952 and from January 1953 to June 1954 could be as large as 75 mrem/wk, or 

3.9 rem/yr. Therefore, the Y-12 coworker doses in this report are expected to be extremely favorable 

to claimants for the period before the start of the monthly and quarterly exchange of the film badge 

dosimeters in the late 1950s and early 1960s (see Table 6-2).

Table 7-2 contains the 50th- and 95th-percentile values of the gamma dose for construction trade 

workers who meet the criteria in Section 3.0 of ORAUT-OTIB-0052 (ORAUT 2007b). These 

percentile values, which are based on the annual values in Table 7-1, were calculated using the 

guidance in Section 8.0 of ORAUT-OTIB-0052 and should not be used for workers who do not meet 

the specified criteria.

Table 7-2. Annual coworker external doses (mrem) with 

gamma and beta doses modified for construction trade 

workers in accordance with ORAUT-OTIB-0052. 

Year

Gamma dose (mrem) Beta dose (mrem)

95th 

percentile

50th 

percentile

95th 

percentile

50th 

percentile

1950 780 780 780 780

1951 780 780 780 780

1952 4,324 2,877 5623 1300

1953 5,392 1,300 7429 2475
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 17 of 21

1954 4,542 1,300 11843 3039

1955 3,294 780 11482 3241

1956 2,227 1,039 8404 2541

1957 1,873 1,002 7777 2384

1958 2,210 1,185 4470 1745

1959 1,576 561 3928 875

1960 1,508 526 5093 894

1961 669 199 2322 91

1962 708 221 2257 101

1963 486 63 1464 82

1964 538 83 1578 97

1965 517 136 1083 70

1966 651 104 1185 118

1967 503 81 1014 81

1968 362 179 897 48

1969 492 160 624 52

1970 494 153 863 53

1971 437 136 469 47

1972 273 62 586 48

1973 259 56 510 60

1974 494 112 614 60

1975 221 58 613 60

1976 233 63 410 89

1977 203 55 350 57

1978 289 102 385 57

1979 200 60 571 71

8.0

Where appropriate in this document, bracketed callouts have been inserted to indicate information, 

conclusions, and recommendations provided to assist in the process of worker dose reconstruction. 

These callouts are listed here in the Attributions and Annotations section, with information to identify 

the source and justification for each associated item. Conventional references, which are provided in 

the next section of this document, link data, quotations, and other information to documents available 

for review on the Project’s Site Research Database.

ATTRIBUTIONS AND ANNOTATIONS 

[1] Watkins, Janice P. Oak Ridge Associated Universities. Biostatistician. March 2007. 

As discussed in ORAUT-RPRT-0032, Historical Evaluation of the Film Badge Dosimetry 

Program at the Y-12 Facility in Oak Ridge: Part 1 – Gamma Radiation (ORAUT 2005b), for 

gamma dose and ORAUT-OTIB-0046, Historical Evaluation of the Film Badge Dosimetry 

Program at the Y-12 Plant in Oak Ridge, Tennessee: Part 3 – Beta Radiation (ORAUT 

2007a), for beta doses, standard statistical distributions, including the lognormal, do not fit 

either the gamma or beta recorded doses well before 1957. Therefore, dose reconstructions 

that require best-and-final dose estimates should be based on tables of GMs and GSDs that 

were obtained from regression analysis based on a subgroup of workers with numerous doses 

both before and after 1961. The results of these regression analyses allow for the estimation 

of radiation doses to workers starting in May 1948 when the Union Carbide Corporation 

Nuclear Division assumed management of the Y-12 Plant and the Plant mission changed from 

the electromagnetic enrichment of uranium to the processing of uranium and other nuclear 

materials (ORAUT 2005b, 2007a).
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 18 of 21

[2] Kerr, George D. Oak Ridge Associated Universities. Health Physicist. March 2007.

The film badge period ended in 1979 as film dosimeters at the Y-12 site and other Oak Ridge 

sites were largely replaced by TLDs (McLendon et al. 1980; Souleyrette 2003; ORAUT 

2007a). The practice of monitoring all employees was continued during the TLD monitoring 

program, the TLD dosimeters were exchanged quarterly, and the MDL was approximately 10 

mrem (Souleyrette 2003; ORAUT 2006). Therefore, the TLD data from the Y-12 site and other 

Oak Ridge sites are sufficiently comprehensive to ensure that a dose reconstruction can be 

carried out for all workers with a potential for external exposure during the TLD dosimetry 

period. 

[3] Kerr, George D. Oak Ridge Associated Universities. Health Physicist. March 2007.

There were very few locations at the Y-12 Plant where neutron exposures were routinely 

possible; in these cases, personnel monitoring was provided by neutron-sensitive films (Emlet 

1956). During 1952 to 1956, for example, there were only 375 positive quarterly neutron 

doses among 143 Y-12 workers. If a worker had no positive neutron doses before 1962, it is 

unlikely that the worker experienced any neutron exposure at the Y-12 Plant (ORAUT 2005c).

[4] Tankersley, William G. Oak Ridge Associated Universities. Industrial Hygienist. March 2007. 

Comparisons were made between the CER database and original plant documents in relation 

to total number of workers monitored by year and department, cumulative annual doses for 

individuals and groups, magnitude of particularly outstanding results, specific years of 

monitoring for individuals, count of doses within or exceeding regulatory limits, average annual 

exposures for multiple years, count of monitoring results within dose ranges, and others. 

Results of the comparisons provided strong evidence of the reliability and completeness of the 

CER database. Specific documents that contained the data with which comparisons were 

carried out included the following:

• Y-12 Plant Health Physics Progress Report for Period July 1 1951 to December 31, 1951

(UCNC 1952);

• Y-12 Plant Quarterly Health Physics Report, Third Quarter CY 1962 (UCNC 1963b); 

• Y-12 Plant Quarterly Health Physics Report, Fourth Quarter CY 1962 (UCNC 1963a); and 

• “Cumulative External Radiation Exposures” (McLendon 1957). 

[5] Watkins, Janice P. Oak Ridge Associated Universities. Biostatistician. March 2007. 

The External Dose Reconstruction Implementation Guideline (NIOSH 2007) mandates the 

assignment of missed dose for periods of employment when badge readings were zero 

regardless of whether the worker’s tasks involved potential for external radiation exposure. To 

maintain consistency, doses based on coworker data for unmonitored periods of employment 

should also be augmented for possible missed dose.

[6] Kerr, George D. Oak Ridge Associated Universities. Health Physicist. March 2007.

Recently, two documents were found that provided new information on the changes in 

frequency of film badge exchange. These documents, McLendon (1958) and Reavis (1958), 

were not available when some previous Y-12 reports were written. 
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 19 of 21

REFERENCES

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Oak Ridge, Tennessee, June. [SRBD Ref ID: 16474].

BWXT Y-12, 2000, Recycled Uranium Mass Balance Project Y-12 National Security Complex Site 

Report, Y/LB-16,036, Rev. 1, Y-12 National Security Complex, Oak Ridge, Tennessee, 

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Armstrong (U.S. Atomic Energy Commission, Oak Ridge Operations), Union Carbide Nuclear 

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Atomic Energy Commission), Union Carbide Nuclear Company, Oak Ridge, Tennessee, 

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McLendon, J. D., 1957, “Cumulative External Radiation Exposures,” memorandum to J. S. Reece et 

al., Union Carbide Nuclear Company, Oak Ridge, Tennessee, July 1. [SRDB Ref ID: 23622]

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3694]

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Corporation, Y-12 Plant, Oak Ridge, Tennessee, March 23. [SRDB Ref ID: 8589]

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ORAUT (Oak Ridge Associated Universities Team), 2005a, External Radiation Monitoring at the Y-12 

Facility During the 1948-1949 Period, ORAUT-OTIB-0047, Rev. 00, Oak Ridge, Tennessee, 

September 20.
Document No. ORAUT-OTIB-0064 Revision No. 00 Effective Date: 08/03/2009 Page 20 of 21

ORAUT (Oak Ridge Associated Universities Team), 2005b, Historical Evaluation of the Film Badge 

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ORAUT-RPRT-0032, Rev. 00, Oak Ridge, Tennessee, April 13. 

ORAUT (Oak Ridge Associated Universities Team), 2005c, Historical Evaluation of the Film Badge 

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11.

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ORAUT (Oak Ridge Associated Universities Team), 2007a, Historical Evaluation of the Film Badge 

Dosimetry Program at the Y-12 Plant in Oak Ridge, Tennessee: Part 3 – Beta Radiation, 

ORAUT-OTIB-0046, Rev. 00, Oak Ridge, Tennessee, June 22. 

ORAUT (Oak Ridge Associated Universities Team), 2007b, Parameters to Consider When 

Processing Claims for Construction Trade Workers, ORAUT-OTIB-0052, Rev. 00 PC-1, Oak 

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External Dose Assignment, ORAUT-OTIB-0020, Rev. 02, Oak Ridge, Tennessee, 

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Pearson, K., 1896, “Mathematical Contributions to the Theory of Evolution; III. Regression, Heredity 

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